If you want to know how to logout from Facebook on iPhone then you are at the right place. Below are the instructions to logout from Facebook.
1 Open Facebook App on your device
2 Now Tap on the Three Horizontal line
3 Tap on Setting and Privacy
4 Now Click on Security and Login
5 Now you are able to see the device name where you account is logged in under the ‘Where You Logged In’
6 Tap on Vertical dots
7 Now Click on Logout button

Read More: https://onlinegeeks.net/log-out-of-facebook-messenger-on-android-ios/